Wound healing is a complex process that some researchers divide into 3 phases of evolution: inflammatory phase, proliferation, and remodeling (1). The inflammatory phase is the first response to an injury and involves multiple responses that include both a cellular and chemokine/cytokine response. The response includes blood coagulation, infiltration of leukocytes, etc. This first phase of response leads to the initiation of the proliferative response for wound healing. In fact, these two first phases overlap and multiple factors influence the phases. An important part of the proliferative phase is the formation of epithelium to cover the wound surface. The epithelialization reaction occurs somewhat in parallel to the growth of granulation tissue that is required to fill the wounds “empty” space. According to Li et al (1), the granulation tissue formation is the result of the proliferation of fibroblasts deposition of collagens and other materials along with an angiogenic process for the formation of new blood vessels. Finally, the third phase is a remodeling phase that involves restoring the structural integrity and functional aspects of the site (1). Every phase of the wound healing process can be influenced by factors such as infection, that will either increase the tissue damage and/or prolong the healing time, as well as dead skin, bleeding, mechanical damage (compression of tissue and friction), dryness, etc.
There are several types of wounds, but they can generally be summarized as either acute or chronic. Acute wounds normally heal without delay and complications, and include burns, traumatic injuries and surgical wounds. Chronic wounds are those that involve a disruption of the wound healing process that results in consequences such as a prolonged time to heal, recurrence or simply non-healing (1). Chronic wounds include venous leg ulcers, pressure sores/ulcers, ischemic ulcers, diabetic ulcers, etc.
Management of Wounds
Each wound is unique and multiple factors influence the methods used to help heal. These factors include the location and size of the injury, the type of injury (e.g. incision, burn), depth of the wound and other tissues involved in injury (i.e., nerves), foreign material in the wound as well as infection, complications during healing that prolong healing time, and genetic or pathophysiological factors influencing the different parameters of healing.
The type of wound closure plays a major role in the healing process. Closure by primary intent is defined as wound closure immediately following the injury and prior to the development of the granulation tissue. Healing by primary intent ultimately leads to the fastest healing and optimal cosmetic result. Closure by secondary intent is defined as the process where wounds heal on their own without surgical closure. Closure by tertiary intent is defined as a first treatment phase where the wound is cleaned and dressings are applied and a second phase several days later for wound closure.
Methods of treating a wound may include one or more steps as necessary to facilitate healing, prevent infection and complications, limit scarring and hyperpigmentation, etc. Treatment may include cleaning the wound to remove foreign material; removing dead skin; closing (in the case of large wounds) with stitching type materials (e.g., sutures); dressing the wound; relieving pain; and treating signs of infection.
In the case of chronic wounds such as pressure or diabetic ulcers, additional treatments may be required. These are generally aimed at trying to improve blood flow to the site of injury to promote healing of the wound/ulcer. Methods involving the use of absorbent dressings and compression bandages typically help improve blood flow.
In addition to the above treatment methods, various substances, both naturally occurring and synthetic, may be employed to promote healing of skin tissues. These are often applied directly to the area of the wound or sore in the form of a lotion or ointment, or incorporated into a bandage, dressing or other device to promote healing while the device is in use.
For example, U.S. Pat. No. 5,266,318 describes a composition for treatment of irradiated skin, open sores, wounds and abrasions. This composition is comprised of an aloe vera gel extract, allantoin and lavender essential oil.
Another composition for the treatment of wounds and related conditions is described in U.S. Pat. No. 5,879,717, which is comprised of a sugar, iodine and a glycol or water vehicle, and is specifically designed for use in veterinary medicine.
A further composition, which is described in U.S. Pat. No. 5,980,875, is prepared by mixing honey with oil, a gelling agent, an emulsifier and other components, and is used for the treatment of Herpes, cold sores, burns, skin allergies and other wounds.
Additionally, U.S. Pat. No. 6,099,866 describes a combination of beeswax with oil and optionally water to produce a composition for treatment of various burns and abrasions.
As can be seen, numerous compositions and combinations are known to assist in the treatment and healing of wounds and skin injury. Nevertheless, research continues in this area in order to develop new compositions with improved effectiveness and/or reduced side-effects.